Cycling valve



H. L. BURNS CYCLING VALVE Oct. 25, 1966 Filed Nov. 18, 1963 INVENTOR.HENRY L. BURNS BY 34 M Attorney United States Patent 3,280,832 CYCLINGVALVE Henry L. Burns, Beaverton, 0reg., assignor to Retec, Inc.,Portland, Greg, a corporation of Oregon Filed Nov. 18, 1963, Ser. No.324,382 11 Claims. (Cl. 137-63) This invention relates to a cyclingvalve without moving parts and has particular reference to a cyclingvalve for a resuscitator, although the valve is of general applicationand is not limited to resuscitators.

Resuscitors have two general classes of use. First, they are used tomaintain breathing in situations where respiration has been stopped dueto suffocation as in drowning, electric shock, poisoning, paralysis,etc. The second field of use is to assist breathing in the therapy ofpartial paralysis, emphysema, asthma, post operative removal ofanesthetic gases, etc.

Resuscitators are normally limited by practical considerations to firedepartments, public first aid facilities, public swimming pools,hospitals, hazardous industries, sick room rental agencies, etc. Costand inconveniences has precluded location of resuscitators in homeswimming pools, in utility company service trucks, in home therapyexcept on a rental basis, and other long range risk situations. Anotherdisadvantage of conventional resuscitators is the existence of ratherdelicate parts including the cycling valve and parts associatedtherewith, such as springs, magnets, etc., which are subject to stickingand deterioration in long periods of non-use. However, the very natureof the respiration accidents is such that immediate availability of aresuscitator is highly desirable in the private as well as the publicenterprises mentioned above.

Basic components of a resuscitator are: One, a source of gas undercontrolled pressure; two, a means of applying this gas pressureintermittently, and, three, a means coupling this intermittent gaspressure to the patients lungs. The usual gas pressure system consistsof a high pressure storage cylinder, cylinder shut-off valve, a means offilling or exchanging cylinders, a means of indicating the amount of gasin the cylinder, pressure reduction means and an outlet pressureregulator. The usual intermittent control consists of inhalation andexhalation valves triggered from one mode to the other via some pressuresensitive means. The usual coupling to the patient consists of abreathing tube and an oral-nasal face mask. Various refinements,operator adjustments and performance features, such as suction in theexhalation mode, may be found in the art but the three basis componentsof gas supply, cycling means and patient coupling are a requirement ofall automatic and semi-automatic resuscitators.

The key component of a resuscitator is the cycling valve, both from thestandpoint of performance and from the standpoint of total cost of thesystem. But a simple, inexpensive cycling valve may not reduce theoverall cost and convenience if the gas supply system must still be madeup of cylinders, gauges, valves and high performance pressureregulators.

The general object of the present invention is to provide a cyclingvalve for resuscitators and other purposes which has no moving parts.Other objects are to provide a resuscitator which is simple inconstruction, requires no maintenance, has maximum reliability, is easyto use and inexpensive to manufacture. A more particular object is toprovide a new and improved cycling valve which obviates the necessityfor gas cylinders, gauges, manual valves and pressure regulatorsnormally required to operate conventional resuscitators.

The key component of the present invention is a cycling valve which issimple in construction and which allows the use of 21 directly connectedgas blower in place of the usual storage cylinder and array of controldevices associated therewith. This cycling valve has no moving partsother than the stream of air which flows through it. Use of aninexpensive electric gas pressure blower for the gas supply of aresuscitator has not been commercially successful heretofore because theintermittent off-on action of the conventional cycling valves createwide pressure fluctuation in the blower output which must be levelledout by the same expensive regulating and accumulator components of thecompressed gas cylinder system.

The invention will be better understood and additional objects andadvantages will be appreciated from the following detailed descriptionof the preferred embodiment illustrated on the accompanying drawing.Various changes may be made, however, in the details of construction andarrangement of parts and, as previously stated, the cycling valve may beused for other purposes. All such modifications within the scope of theappended claims are included in the invention.

In the drawing:

FIGURE 1 is a perspective view of a resuscitator embodying theinvention, the cycling valve being removed from the blower;

FIGURE 2 shows the construction of the cycling valve;

FIGURE 3 is a fragmentary sectional view taken on the line 3-3 of FIGURE2;

FIGURE 4 is a fragmentary sectional view taken on the line 4-4 of FIGURE2;

FIGURE 5 is a fragmentary sectional view taken on the line 55 of FIGURE2; and

FIGURE 6 is a fragmentary sectional view taken on the line 66 of FIGURE2.

Referring first to FIGURE 1, numeral 1 designates a positivedisplacement blower driven by an electric motor 2. The blower draws inair from the atmosphere through intake 3 and discharges it in continuousflow through outlet 4. These inlet and outlet ports are incorporated ina mounting plate 5 having screw holes 6 for mounting the cycling valve10.

The valve 10 comprises two fiat plates 11 and 12 secured together byscrews 13 or other suitable means. On the inlet end of the valve astandoff plate 14 is secured to the plate 12 and screws 15 are providedto engage the holes 6 for securing plate 14 and the valve plates tomounting plate 5. When the valve is thus mounted on the motor and blowerunit, the valve inlet port 20 is in registering communication withblower outlet port 4, and standoff plate 14 holds the valve plate 12spaced from the blower inlet port 3 so that the latter is notobstructed. The valve 10 has two discharge ports 21 and 22, the formerbeing connected with a flexible tube 25 leading to an oral mask 24 andthe latter being open to atmosphere. Outlet 22 is restricted at 23.

The details of construction of valve 10 are shown in FIGURE 2. Plate 12is a thick plate having grooves recessed into one surface, all thegrooves being of uniform depth with square sides and flat bottoms toform air passageways of rectangular cross section. Plate 11 is a fiatplate which is attached to plate 12 over the grooves, converting them toenclosed airways. It is the pattern of these airways that determines thefunctioning properties of the cycling valve.

Air enters the valve in continuous steady flow through the inlet 20 andproceeds through a converging airway 30 to a restricted rectangularnozzle orifice 31. Downstream from nozzle 31 the airway widens at 32between divergent side walls and separates into a mask branch 33 and anoutlet branch 34. These two airway branches diverge from each other onopposite sides of a wedge shaped divider 35 which is aligned with thecenter line of nozzle 31. The walls of the branches 33 and 34 preferablydiverge slightly as they approach the outlets 21 and 22. Branch 33 andoutlet 21 provide free and unrestricted flow to the mask.

In the mask branch 33 the side wall 36 farthest from the Outlet branch34 is provided with a longitudinal series of narrow slot openings 37beginning just downstream from the apex of divider 35. These slots ventthe surface 36 into' a feed back airway 38 which passes around to abiasing jet opening 40 immediately at the outlet of nozzle 31 on itsopposite side and at right angles to the nozzle center line.

Air entering at 20 is converted from a predominantly pressure state to avelocity state via the converging airway 30 approaching nozzle 31. Asthe air stream injects from the nozzle into the widened downstream area,a relative vacuum is created at the biasing jet opening '40 therebyestablishing a flow of air from openings 37 through passageway 38 andjet opening 40 to impinge on the air stream from nozzle 31. The effectof this air jet from opening 40 is to bias the flow from nozzle 31 intothe mask airway branch 33. Otherwise, the nozzle flow would tend todivide equally into 'both branches 33 and 34.

Once the main stream contacts airway side wall 36, boundary layereffects cause all of the flow from nozzle 31 to lock into the maskbranch 33. If the mask outlet is a compliant but dead end system, suchas a patients lungs, flow will continue from mask outlet 21 until theelastic resistance of the lungs equals the available flow pressurecausing flow through mask branch 33 to diminish and force the nozzleairstream to switch into outlet branch 34 where the boundary layerphenomenon on wall 45 causes the air stream to lock into the outletbranch 34. This relieves the air pressure in the patients lungs allowingthe elasticity of the rib cage structure to start exhalation.

As long as exhalation flow continues from the mask connection 21 backdown airway 33, its impingement on the nozzle air stream will enhancethe outlet mode and overpower the biasing efiect of flow from opening40. Relatively free flow through the outlet branch 34 plus boundarylayer effects of flow on wall 45' plus such aid from the mask branch 33backfiow tends to hold flow in the outlet mode even to the extent ofcreating a partial vacuum at the mask connection 21. Outlet restriction23 brings this mask vacuum producing tendency under control by limitingair velocities through outlet branch 34 and, in this resuscitatorapplication, a terminal pressure of atmosphere or very slight vacuum isthe optimum point at which to switch the nozzle air stream into the maskbranch 33 to complete the cycle. When exhalation 'backflow through maskbranch 33 ceases, or almost ceases, this backflow can no longeroverpower the biasing effect of flow from opening 40 and the biasing jetthen switches the main flow from nozzle 31 back into the mask branch tostart the next inhalation phase or mode.

In order to achieve maximum efiiciency conversion of inlet supplypressure to the build-up of mask pressure at switch-over point, theboundary layer lock-up on wall 36 is further enhanced by turbulenceattenuating flow into slots 37. The diverging walls of branches 33 and34 produce efficient conversion of velocity pressure into staticpressure. The interconnection of bias jet 40 and holding slots 37 has adiminished effect during the outlet or exhalation flow mode since thevacuum tendency in the mask branch 33 also tends to attenuate the 'biasjet fiow which, if acting unrestricted, would cause switching fromoutlet to mask before the desired zero or slight vac uum was attained.

A typical pressure flow cycle attainable with the present cycling valveis as follows: Starting with the onset of the inhalation mode,unrestricted flow exits from the mask connection 21 and, as the lungsexpand elastically, produces an increasing back pressure until boundarylayer eitects and biasing jet can no longer lock the gas flow into themask branch 33. For resuscitation this should occur at five to sixinches water column mask pressure (one inch water equal 0.036 p.s.i. or1.87 mm. mercury).

After switching to the exhalation mode, the inlet nozzle air stream plusexhaled gases flow out the outlet branch 34 until exhalation flow hasdiminished to zero or near zero when the biasing jet can switch thenozzle air into the mask branch 33 to start a new cycle. This shouldoccur when mask pressure is between zero and minus one-half inch watercolumn. To maintain these cycling pressures an inlet pressure between 9and 10 inches water column is used. It will be noted that the cyclingvalve is predominantly flow sensitive. Inlet pressure from a one cubicfoot per minute constant displacement flow has less than ten percentvariations during both phases of the cycle except for a very shortpressure spike at the instant of switch-over from inhalation toexhalation.

Known fluid switching devices used predominantly in fluid poweredamplifiers and computing equipment, and particularly those designed forsonic flow velocities and high energy jets, are not suitable for thepresent purpose. An attempt to apply these known principles directly, aswell as many of the published variations of oscillator and feed-backsystems, resulted in entirely unsatisfactory performance as aresuscitator. With the computer configurations, the best inlet pressureto maximum mask pressure ratio obtained was thirty inches water inlet tosix inches at the mask; this is undesirable and dangerous. Exhalationpressures lower than one inch above atmospheric were unattainable andswitching action from inhalation to exhalation even then was notpositive. Applicants new arrangement has produced gross changes inperformance. The turbulence reducing holding slots 37 in communicationwith biasing jet 40 are a novel and essential feature of the presentcycling valve which impart the de sired characteristics, particularlyfor a resuscitation anplication.

The stable and relatively low inlet pressure requirement (nine to teninches water) makes use of -a simple positive displacement gas blowerfeasible as an inexpensive part of the resuscitator assembly. Such a lowinlet pressure is achieved by minimizing pressure drop through maskbranch 33, the turbulence reducing slot 37 being an importantcontributing factor. The cycling pressure flow pattern matches thegenerally accepted ideal for resuscitators and produces a desiredbreathing rhythm when the patient is not breathing. The unit sensitivityto flow allows the patient to set the breathing rhythm with a minimumeffort when he is breathing. A blocked airway to the patients lungs willcause rapid cycling providing a clue to the operator that the lungs arenot being ventilated and that appropriate action must be taken. A steadynon-cycling rnode would indicate to the operator that there is anexcessive leak in the face mask.

In summary the following important features are emphasized.

(1) The cycling valve performance characteristics are such that a simpledirect connected gas blower may be used.

(2) The cycling valve has only two parts, both stationary-a groovedplate and a cover plate which can be produced by inexpensivemanufacturing techniques.

(3) The cyclingvalve has no moving parts thereby assuring long life andmaximum reliability. There are no valve seats to develop leaks, nosliding or pivoting parts to freeze up, no pressure sensing diaphragmsto deterioate, no springs to maintain in adjustment.

(4) Performance characteristic meet the ideal intermittent pressurespecifications for resuscitators and, if future clinical study shouldshow greater suction pressures are desirable, the cycling valve hasthese capabilities also (by enlarging outlet orifice restriction 23). A

The cycling valve is useful wherever a repeating fill and dump fluidcycle is desired in connection with a fluid capacitance. For example,the valve 'may be used as a' liquid volume indicator in a closed tank,the cycle frequency being a measure of the volume which is not occupiedby liquid. When the gas or vapor capacitance is small (tank nearly fullof liquid), the valve will cycle rapidly and, as the gas or vaporcapacitance increases (as liquid is withdrawn from the tank), the valvewill cycle more slowly.

For such other applications, it may be noted that stable and uniformcycling can be obtained with pressures lower than 0.1 inch water columnand flows well within the laminar region. In the lower pressure ranges acentrifugal blower may be used instead of a positive displacement type.

Having now described my invention and in what manner the same may beused, what I claim as new and desire to protect by Letters Patent is:

1. A reversing valve for coupling with an external fill and dump fluidcapacitance of substantially limited capacity comprising an inletnozzle, a flow divider in front of said nozzle, a pair of divergingbranch passageways on opposite sides of said divider, one of saidbranches terminating in an outlet and the other branch terminating in aconnection for said capacitance, a constantly operative, unidirectionalbiasing jet orifice adjacent said inlet nozzle arranged to divert thenozzle flow into said capacitance branch, and an opening in the wall ofsaid capacitance branch opposite said divider supplying said biasing jetorifice with fluid from said capacitance branch, said inlet nozzleconstituting the only functional source of fluid to said valve and saidbiasing jet orifice being the only biasing jet orifice in the valve.

2. A reversing valve as defined in claim 1, said opening comprising aseries of slots in said wall arranged to sustain boundary layer flowover the slots.

3. A reversing valve as defined in claim 2, said series of slotsextend-ing downstream from a point approximately opposite the apex ofsaid divider.

4. A valve comprising an inlet nozzle, a pair of outlets, a flow dividerin front of said nozzle, a pair of diverging branch passageways onopposite sides of said divider leading to said outlets, a single biasingjet orifice on one side of said nozzle, and slot openings in the wall ofsaid branch opposite said orifice for supplying said orifice with fluidfrom said branch, said slot openings being arranged to sustain boundarylayer flow over the slots, and said inlet nozzle constituting the onlyfunctional source of fluid to said valve.

5. A reversing valve for an external fill and dump fluid capacitancecomprising an inlet nozzle, a flow divider in front of said nozzle, apair of branch passageways on opposite sides of said divider, one ofsaid passageways being a capacitance branch for connection with thecapacitance and the other passageway being an outlet branch for saidcapacitance and for the inlet nozzle flow, and a unidirectionalconstantly operative biasing jet orifice adjacent said nozzle andsupplied from said capacitance branch to divert the nozzle flow intosaid capacitance branch until the capacitance is filled, saidcapacitance branch being subject to reverse flow from the capacitanceand arranged relative of said jet orifice to direct said reverse flow inopposition to the biasing jet and render the biasing jet ineffectivethough constantly operative during the interval of reverse flow.

6. A fill and dump fluid capacitance system comprising a reversing valvehaving an inlet nozzle, a flow divider in front of said nozzle, a pairof diverging branch passageways on opposite sides of said divider, oneof said branches terminating in an outlet, a receiver of substantiallylimited capacity connected with the terminal end of the other branch, aconstantly operative, unidirectional biasing jet orifice adjacent saidnozzle and arranged to divert the nozzle flow into said receiver branch,and an opening in the wall of said receiver branch opposite said dividersupplying said biasing jet orifice with fluid from said receiver branch.

7. A fill and dump fluid capacitance system comprising a reversing valvehaving an inlet for connection to a constant flow gas source, an outletin said valve, a receiver of substantially limited capacity connected tosaid valve, branching passageways in said valve arranged to convey gasflow from said inlet to said outlet and receiver, unidirectional,constantly operative means adjacent said inlet to bias said flow intosaid receiver branch until the receiver is filled, cessation of flowthrough said receiver branch when the capacitance is filled creating aback pressure and switching said inlet flow from said source throughsaid outlet branch permitting said receiver to discharge through saidoutlet branch along with said inlet flow from said source, saiddischarge creating a reverse flow in said receiver branch, said receiverbranch being arranged to direct said reverse flow so as to overcome theeffect of said biasing means, cessation of said reverse flow renderingsaid biasing means again effective to start a new receiver filling mode.

8. In a resuscitator, a reversing valve having an inlet, an air supplyconnected to said valve inlet, an outlet to atmosphere in said valve, apatient face mask connection in said valve, branching airways in saidvalve arranged to convey air flow from said inlet to said outlet andsaid mask connection, unidirectional biasing jet means supplied fromsaid mask connection and adjacent said inlet for continuously biasingsaid flow into said mask branch to start an inhalation mode, cessationof flow through said mask branch when the patients lungs are filled withair creating a back ,pressure switching said inlet flow from said supplythrough said outlet branch and permitting exhalation through said outletbranch along With said inlet flow from said source, said exhalationcreating a reverse flow in said mask branch, said mask branch beingarranged to direct said reverse flow so as to overcome the effect ofsaid biasing means, cessation of said exhalation reverse flow renderingsaid biasing means again eifective to start a new inhalation mode.

9. In a resuscitator, a reversing valve having an inlet nozzle, aconstant flow air pump having an outlet connected to said valve inlet, aflow divider in front of said nozzle, an outlet to atmosphere in saidvalve, a patient face mask connection in said valve, divergent branchingairways on opposite sides of said divider arranged to convey air fl-owfrom said inlet to said outlet and said mask connection, a constantlyoperative, unidirectional biasing jet orifice arranged to divert saidflow into said mask branch to start an inhalation mode, and slots in thewall of said mask branch opposite said divider supplying said biasingjet orifice, cessation of flow through said mask branch when thepatients lungs are filled with air creating a back pressure switchingsaid inlet flow from said pump through said outlet branch and permittingexhalation through said outlet branch along with said inlet flow fromsaid pump, said exhalation creating a reverse flow in said mask branch,said mask branch being arranged relative to said jet orifice to directsaid reverse flow in opposition to said biasing jet, cessation of saidexhalation reverse flow rendering said biasing jet again effective tostart a new inhalation mode.

10. A resuscitator as defined in claim 9 including means to control theminimum exhalation pressure, said means comprising a restriction in saidoutlet.

11. A reversing valve having an inlet, an outlet, and a fluidcapacitance connection for an external fill and dump fluid capacitanceof substantially limited capacity branching passageways comprising anoutlet branch and a capacitance branch arranged to convey a fluid flowfrom said inlet to said outlet and to said capacitance connection,respectively, and eflectively unidirectional biasing means adjacent saidinlet and acting continuously to bias said flow into said capacitancebranch, attainment of the limit of capacity acting to overcome theeffect of said biasing 7 8 means and switch said inflow through saidout-let branch I OTHER REFERENCES to evacuate 934d capacitance branch-Future for Fluid Amplifiers, Electronics, Mar. 25,

References Cited by the Examiner 1960 UNITED STATES PATENTS ReferencesCited by the Applicant 1,136,517 4 1915 Drager 1289 UNITED STATESPATENTS 1,488,442 3/1924 Sohro-der 12s-29 3,001,539 9 19 1 z- 2,598,5255/1952 Fox 12829 gigg 2,948,148 8/1960 An frevllle et a1. 10 1/1962Warren 3,024,805 3/1962 Horton "137-815 22 74 2 19 -1, 1% 3,114,39012/1963 Glattli 1378,1.5 3,030,979 4/1962 Reilly. 3,185,166 5/1965Horton et a1. -137 s1.5. 3,080,886 3/1963 Severwn- 3,204,652 9/1965Bauer 137-815 15 3,093,306 6/1963 Warren! FOREIGN PATENTS M. CARYNELSON, Primary Examiner.

1,278,781 11/ 1961 France. S. SCOTT, Assistant Examiner.

1. A REVERSING VALVE FOR COUPLING WITH AN EXTERNAL FILL AND DUMP FLUIDCAPACITANCE OF SUBSTANTIALLY LIMITED CAPACITY COMPRISING AN INLETNOZZLE, A FLOW DIVIDER IN FRONT OF SAID NOZZLE, A PAIR OF DIVERGINGBRANCH PASSAGEWAYS ON OPPOSITE SIDES OF SAID DIVIDER, ONE OF SAIDBRANCHES TERMINATING IN AN OUTLET AND THE OTHER BRANCH TERMINATING IN ACONNECTION FOR SAID CAPACITANCE, A CONSTANTLY OPERATIVE, UNIDIRECTIONALBIASING JET ORIFICE ADJACENT SAID INLET NOZZLE ARRANGED TO DIVERT THENOZZLE FLOW INTO SAID CAPACITANCE BRANCH, AND AN OPENING IN THE WALL OFSAID CAPACITANCE BRANCH OPPOSITE SAID DIVIDER SUPPLYING SAID BIASING JETORIFICE WITH FLUID FROM SAID CAPACITANCE BRANCH, SAID INLET NOZZLECONSTITUTING THE ONLY FUNCTIONAL SOURCE OF FLUID TO SAID VALVE AND SAIDBIASING JET ORIFICE BEING THE ONLY BIASING JET ORIFICE IN THE VALVE.